Compression coating tablet press



July 26, 1960 w. A. DOEPEL ET AL 2,946,298

COMPRESSION COATING TABLET PRESS Filed Nov. 13, 1957 &

3 Sheets-Sheet 2 ME AS URE 2& ILL

LEVEL OFF FILL INVENTORS 3 MLLACE A. DOEPEQHUGHGTOGAE, N g LE0 P Ga 94 W/LL/AMtTPmEN g a 3 z M, mow m N ATTORNEYS 1960 w. A. DOEPEL ET AL 2,946,298

COMPRESSION COATING'TABLET PRESS Filed Nov. 13 1957 3 Sheets-Sheet 3 INVENTORS Manes A. 005 a ,HUGH 0. 06.49,

60 A? 640%? & M/ILL/AM t. PALEN 1 KM r M ATTORNEYS United States z,94s,29s

COMPRESSION COATING TABLET rnnss 27 Claims. (Cl. 107-1) This invention relates to a compression coating tablet ress. p It has been known for 75 or 100 years at least that medicines in tablet form could be covered with a coating by surrounding the tablet with a quantity of powder and compressing the powder under pressure to form an envelope around the tablet.

It has also been known for many years that this coating could be applied by an apparatus; first, utilizing individually made tablets, and subsequently using continuously operating machines for turning out tablets in large production.

An early patent on compressed tablets is the patent to Carter 207,013, dated August 13, 1878. Examples of apparatus for coating tablets are the Noyes Patent 568,- 488, dated September 29, 1896, and the patent to Stokes 1,248,571, dated December 4, 1917. A more recent disclosure is found in the Wolff Patent 2,700,938, dated February 10, 1955.

It is an object of the present invention to provide an improved coating device or compression coating of powdered materials which will have a greater production than any previously known machine, and it will have distinct advantages over the present apparatus for accomplishing this purpose. Specifically, it is an object to provide a machine which centers a core tablet within the coating and which provides a desired quantity of coating on each side of the tablet.

It is a further object to provide a device which can be adapted to various sizes and shapes of core tablets and one which is practically fool proof in operation in that a tablet cannot be made without a core.

It is an object of the invention to provide safety devices and a basic construction which prevents the formation of a solid tablet unless a core is included therein.

Another object of the invention is a provision of a machine which picks up cores and presses them positively into a lower charge of material after it has been moved to a position vertically where the die pocket may receive the upper charge. A control device for the vertical position of the lower charge is provided to permit this positive placement of the core.

Numerous other objects and features of the invention will be apparent in the following description and claims.

Drawings accompany the invention and the various views thereof may be briefly described as:

Figure 1, a plan view of the main operating parts of the machine showing their relationship;

Figure 1a, a small elevation of the entire machine;

Figure 2, a plane development of the die punches which are arranged circularly in the die pocket wheel;

Figure 3, certain selected punches in the operation of the machine showing the various stages;

Figure 4, a partial vertical section of the machine showing the relationship of the parts;

Figure 5, a plan view of the air-controlled manifold;

Figure 6, an enlarged view of a pick-up nozzle.

Referring to the drawings:

Core tablet feed and selection A hopper 20 for core tablets is positioned on a vibrating feeder screen 22 which is stepped at 24 to turn over the tablets as they pass through the feeder unit to clean the dust from both sides of the tablet. The tablets move into a circular feeding disc 26 which is rotated by a constantly revolving shaft 28 which drives a drum 30 (Fig. 4) on which the disc 26 is mounted.

The drum 30 is subject to slight vibration by a vibratorunit 32 having an arm 34 and a roller 36 which contacts the drum, and a slight decline at 38 feeds tablets outwardly on this variable speed revolving disc toward the periphery where a core selector or locating ring 40' is rotating in a direction opposite or in same direction 'if desirable, to the feeder plate 26. Selector ring 40 is tablets as they feed toward the pick up ring 40. Thering is mounted to rotate with the ring gear 42 and pick up ring 40 and is spaced upwardly from plate 26 a sufiicient distance to permit cores to pass between the two but close enough to prevent shingling. The ring 60 is also provided with a series of openings 61 on a common diameter. Adjacent the inner portion of the machine, these holes 61 permit pick up nozzles to reach into the ring 40 to lift the core tablets.

On the stationary column 44 is also mounted a spider ring 62 which extends outwardly beyond the plate 26 to provide a stationary annular platform 64 on which the selected cores will ride after leaving disc 26. The pick up ring 40 is provided with internal regularly spaced notches 68 for receiving one or more tablet cores from that quantity of cores which is reaching it from the vibrating plate 26. The notches are angled to the radius toward the tangent to the disc 26 so there is a tendency to sco'op the tablets from the disc. The drag of this stationary ring 64 pulls the cores into notches 68.

The selected cores 70 shown in Figure 1 are positioned the stationary plate 62 where it will pass through openings in the sprocket 42.

The first unit of the device thus consists of a vibrating hopper and screen 22 for furnishing cores to vibrating plate 26 which carries the cores in a Hat position to the reverse or forward rotating ring 40 provided with apertures 68 which position selected cores directly below openings 61 in ring 60 which is rotating with the ring 40.

Core pick up and deposit The second stage of the operation involves picking up the selected cores and transmitting them to a third stage of the apparatus where the cores are deposited and coated. This second stage or phase of the operation is accomplished by two idler guide wheels or toothless sprockets and 82 nested adjacent the sprocket 42 and mounted on shafts 84 and 86 respectively. Between the idlers 80 and 82 is a vacuum tube 90 rotatably mounted in a bearing 92 and associated with a gear 94 and a gear 96 meshing with gear 50 which causes rotation of a vacuum pressure manifold mounted at the top of the column 90 and shown in outline in Figure 1. This manifold 100 is fixed on the top of the column 90 and shown in outline in Figure 1. This manifold 100 consists of a fixed portion 102 on the top of the unit and a rotating portion 104 on the bottom of the unit. The bottom portion of the unit is provided with a series of openings 106, each of which is connected to a tube 108, the purpose ofwhich will be later described.

The fixed part 102 is a semi-circular: shell. forming, a vacuum chamber on the left hand side of the assembly 100 as shown in Figure 5. This shell is mounted for (Fig. 5) to provide a pressure chamber 116 so that selectively the holes 106 in the rotating plate 104 will be subjected to vacuum as they pass under the semicircular vacuum chamber 102, and they will be subjected individually to a pressure above atmospheric as they pass under the chamber 116. Suitable sources of air at the proper pressure can be provided in communications with the column 90 and the pipe 114. Traveling around the idlers 80 and 82 is a chain 120 which carries a plurality of core-transfer nozzle carriers 122 projecting radially outwardly from the chain.

Each of these core-transfer assemblies is hollow and connected to the rotating tube ring 104' moving in synchronism with the outer diameter of the sprockets 80 and 82. Each transfer assembly has a short metal lead tube 124 which joins with the tubes 108 which are flexible and made of preferably a plastic material.

The chain 120 is also engaged with the sprocket 42 as shown in Figure 4 and similarly with a sprocket or ring gear on the press coating die table head to be later described. The core-transfer assemblies consist of a hollow body portion 126 which has a smaller downwardly projecting nozzle 128 which serves as the pick up which contacts the core tablet and, by reason of vacuum in the core-transfer unit, causes a sure adherence to the bottom of the nozzle 128.

Small metal fingers 130 are preferably positioned around the nozzle to mechanically center the core as it moves up to the end of the nozzle 128 (see Figure 6).

14.0- of the machine, there are mounted cams 142 and 1'44 shaped to positively depress and lift the core-transfer assembly at the proper time in the circuit.

In the operation of the second stage of the apparatus, the sprocket assembly will rotate in synchronism with the selector ring 40, which is positioned in register with the holes 61 of the ring so that the. cam 142 acting on. roller 150 can move the finger 128 into the. hole 61 and. cause the. vacuum in chamber 102 to pick upand hold a core. on the end of the nozzle 128.

The cores will. then be moved around by the chain and core-transfer assemblies to a deposit position relative tothepress coating die tablewhich will now be-described.

Core coating operation At the left hand side of Figures 1 and. 4. and in Figures 2 and 3 the mechanism for coating the core tablet is shown: The main element of thissection'ofthe machihe' is of course the die table head or rotating wheel 16. This rotating die table head has a tooth section on the outside for engaging the sprocket chain 120 and moves in synchronism with the chain operation.

The die table head is driven by a motor connected to a gear 162. The sprocketed die table 160 drives chain 129 guided by toothless sprockets and 82 and chain drives sprocket 42. It is provided with a plurality of circumferentially spaced openings 164 and 166. The latter opening beingv provided for receiving a die 168, which in turn has a die bore 170. These openings are spaced to register with the core-transfer nozzles 128 as they pass around on the chain 120 passing around sprocket teeth of die table head 160.

Mounted on the same shaft with the die table is a bottom die head 172 and atop die head 174. The bottom die head 172 is provided with a plurality of circumferentially' spaced holes 176, Figure 2', each of which carries a punch 178 having an actuating head 180 and a punch tip 182. Similarly, the upper die head is provided with a plurality of circumferentially spaced recesses 186, each of which is provided with a punch 188 having an actuating head 190 and a punch tip 192'.

' Each of the bottom punches 178 are controlled" in their vertical movement by a friction plunger 194 of nylon or similar material (Fig. 4) backed by a spring 196 so that any vertical motion of the lower punch in the opening 176 must be obtained by positive actuation of the punch.

Vertical movement of the punches in the upper and lower die heads is accompished by cam operation. As viewed in Figure 2', a raising cam 200. at the upper left hand portion of the drawing has a flange 202 which. engages the, lower side of the actuating ends 190 to move the ends up into a cam track 204 (Figure 4') so that the punches are carried for a substantial portion of their circumferential travel at a predetermined level above the die table 160. Atthe right-hand end as shown in Figure 2 the punches meet a flange 206 on a pull-down cam 208 which causes the punches to lower so that they move substantially tangentially into contact with a pressure roll' 210. Subsequent to contact with the pressure roll, the punches again meet the flange 202 on cam 200 to move into the lift position.

For. control of the lower punches and starting at the extreme left of Figure 2, an ejection cam 220 with an adjustment, plug 222 moves the punches 178 to a top position where it. ejects a. finished tablet 224. Immediately, a pull-down cam. 226 lowers the punches 178 against the friction of plungers. 194 to a level ring 228. A weight adjustment cam; 230,. adjustable by a nut 232, provides accurate measurement for an initial chargeof coatingmaterial. A secondbell-mouthed pull-down cam 234. moves the punch with its charge down to a predetermined level. The. bell-mouthed cam 234 is shaped: toreach the punch heads, or ends 180 regardless of adjustment of cam 230. Subsequently the punches ride on a corepositioning-cam or leveler 236 which is also. adjustable by a knurled nut 238. This corepositioning cam allows accurate adjustment while the core is moved into the lower charge for positive location. therein.

The punches thenride over to a second weight adjustment earn 240;. and after they leave this cam; they are held in position by nylon plugs 194 until. moved by the pressure of the upper punches to substantially tangential relation to the-bottom pressure roll 250. As the punches pass between and leave the pressure roll, they meet theejector cam 220: which raises them. again tothe ejection position. Each of the punches in the lower die head have been numbered from 1 to 33 for convenient reference to Figure 3 which shows thevarious stages of operation aswill' be later-described.

A means is provided for feeding coating material: in granular form to the dies in the die table 160, in the form of a primary feed shoe 260, having a hopper 262 supported 'thereabove and feeding granular material into the primary pocket 264. Additional pockets 266 and 268 are provided in usual manner. Just ahead of the primary feed pocket 264 is a blade 270 which strips away finished tablets and takes them to a discharge chute 272 leading to a hopper 274 and a vibrating duster screen 276. A suitable leveling off blade 278 (Fig. 2) cleans and levels the top of a die cavity after it has been filled.

At the rear of the machine as shown in Figure l, a metering feed table 280 is provided having a plurality of holes 282 of elongate configuration spaced circumferentially. A secondary feed shoe 284 with suitable hopper 286 supplies granular coating material to the feed pocket 288. The feed plate 28%) is so positioned relative to the die table 16-0 that the pocket reservoirs 282 overlie the die pockets 170 as the table 280 moves in synchronism with the die table. The shape of the holes 282 is such that they will dwell over the holes 170 throughout a period of the arcuate movement of the two die table wheels, thus dumping the powder from the top table 280 to the die table 160. A scraper or clean off blade 290 levels and removes excess of the top charge on the core tablet. A composition gear 285 engages the lower punch barrels 178 to cause rotation of the table 280 in synchronism with the die table 160.

Operation In the operation of the device, cores to be coated are deposited in the hopper 20 and carried by the vibratory screen 22 to the vibrating plate 26 which carries the cores outwardly to the ring 49 where they are picked up by the grooves 68 and arranged in a predetermined radial position. As the wheel rotates in the direction of the arrow, the chain 120 is also rotating carrying the coretransfer assemblies 122 in a path coincident with and overlying the holes 16 of ring 60. At a suitable position relative to the machine, the core-transfer assemblies 122 are moved downwardly by the contact of rollers 15% with cam 142, and the projecting fingers 130 on the pick up nozzle 128 will position the core as it is picked up by the suction transmitted from the vacuum chamber 110 through the tubes 108. The selected cores are then moved around the machine to a position overlying the inner periphery of the die plate or table 160.

In the meantime, the die openings 170 in the die table 169 have been filled at the primary feed shoe 260. As shown in Figure 2, the lower die punches 1, 2, 3, 4 and 5 are receiving the charge and are then moved up to be leved ofi finally by the scraper blade 278 so that a predetermined and accurately measured charge can be initially deposited in the die bore. The lower punches are then moved downwardly by the cam 234 to a predetermined level and moved up by adjustable cam 236 to core deposit position. This prevents tipping or dislodgement of the core from center after deposit. It is desirable that the charge with the deposited core be not lowered in the die pocket except under pressure as will be described. The lower punches are supported against falling by the nylon plungers 194.

This stage of operation is shown at plungers 8 to 12. Then, as shown in Figure 2, the core-transfer nozzle 128 gradually moves down into the die bore as the cam 144 urges rollers 150 downwardly against the spring 136 lowering the entire core-transfer housing 122 including the vacuum chamber 126 and the small transfer nozzle 128 which carries the tablet core.

At this point in the operation, the vacuum is cut off and the tubes are opened to atmosphere; thus, permitting the core to remain impressed in the initial charge of granulation in the die bore spaced considerably below the surface of the die table. Under most circumstances it will be desirable to press the core into the bottom charge to position it. As shown at plungers 11, 12, 13 and 14 and 15 of Figure 2, this depositing operation has taken place.

During the impressing of the coreimo the initial charge of granulation, the lower punches are positively controlled in vertical location by adjustable cam 236 which positions the punches to receive the pressure of the core-transfer nozzles.

In the next phase of: the operation, the metering feed table 280 meters a certain quantity of granular coating material into the top of the die bore at stations 19, 20, 21 and 22, and at station 23 scraper or wiper blade 290 cleans 011 the top of the die as the plungers are moved upward, to a carefully adjusted position on cam 240. With the charge now positioned below, above and around the core, it is now subject to compression by downward movement of upper punches on cam 206 and the entire charge lowered to the level bar 244 as the punches approach the pressure rolls 210 and 250 which exert the required amount of pressure to consolidate the coating around the core tablet. Cam 202 rapidly moves upper punches upwardly and the ejection cam 220 then moves the core up to the surface of the die table 160 where it is removed by the blade 270 and the operation repeated.

The pressure area in manifold 116 is discharged into the tubes 108 individually at a point after they deposit the core in the dies of the die table and prior to the pick up of another core. This dusts OK the fingers and cleans chips or particles out of the nozzle 128 making it ready for another pick up. In the event a core becomes jammed in a nozzle, an increased pressure in tube 114 will be reflected on a diaphragm 300 which reacts against a micro switch 302 which in turn actuates a solenoid brake-clutch 304 and causes immediate stoppage of the machine. This safety control can also be supplemented by a feeler finger 306, Fig. 1, which actuates a similar control switch 308 connected to the solenoid brake-clutch.

Also, if for some reason the core has not been deposited, it will be ejected oif the nozzle 128 by the pressure. It should be understood also that if a core is for some reason not picked up from the ring 46, there will be a suction flow through the particular nozzle 128 and tube L108 which has not received a core. This suction will draw out the lower charge of granulation in the die of die table so that only the upper charge is to be found in the die cavity when the cavity reaches the pressure rolls. Since there is only a predetermined and positive degree of pressure motion at the rolls, it will not be sufiiicient to compress the single metered charge of lower granulation into a stable mass. At the ejection point, this charge of loose granulation will crumble and be dusted oii at the vibratory screen 276. This is insurance that there will never be an ejected complete tablet which does not have a core.

What we claim is:

l. A device for coating formed core tablets with a compressed granular coating which comprises a circumferentially recessed feed table, a circumferentially recessed die table, operating on substantially parallel axes, the peripheries of said tables being spaced from each other, sprocket guide wheels positioned to have pe ripheries substantially tangential with each of said first tables, and a sprocket chain engaging peripheral formations on each of said tables and wheels wherein all of said wheels and tables operate with the same peripheral speed, and a sprocket chain operates around said sprocket wheels and between said die tables and feed table, a plurality of vacuum transfer means operating on said sprocket spaced to register with the recesses of said pick up table and said die table, means to raise and lower said means as they approach registry with each of said tables, and means for controlling vacuum in said transfer means to cause pick up of cores from said pick up table and for terminating the effect of the vacuum to cause deposit of said cores in said die table.

2. A combination as defined in claim 1 including also a primary feed station for granular material positioned 7 relative to said die table ahead of the deposit of the core and a secondary feed station positioned relative to said die table to deposit an exactly metered granular charge on top of a deposited core.

3. A combination as defined in claim 2 in which the secondary feed station comprises a circumferentiaily recessed feed table overlapping a portion of the periphery of the die table and having recesses adapted to receive granular material from a pick up point and deposit it in the die bores of the die table as the two tables rotate simultaneously.

4. A combination as defined in claim 1 in which the core feed table comprises a central disc horizontally disposed and tapering from the center downward to the outer periphery, means to rotate said disc in one direction, a ring having a plurality of pick-up recesses on the inner periphery thereof open to said ring periphery, a means to rotate said ring relative to said disc, said openings being spaced circumferentially to register with the pick up means, the ring operating in synchronism with said pick up means.

5. A combination as defined in claim 4 in which the recesses on the inner periphery of the rotating ring are angled slots positioned to approach tangency to the feeding disc.

6. A combination as defined in claim 4 in which a cap ring overlies said pick-up ring to prevent overlapping of cores.

7. A combination as defined in claim 4 in which means is provided to vibrate said feeding disc to accentuate motion of cores deposited thereon toward the outer periphery.

8. A combination as defined in claim 1 in which the core transfer means comprises a body having vacuum passages therein, means for mounting said body on a vertical axis for vertical motion relative thereto, resilient means for urging said bodies upwardly, and cam means positioned adjacent the periphery of said core feeder table and said die table for moving said bodies downwardly for the respective pick up and discharge functions.

9. A combination as defined in claim 8 in which said body has a core-transfer nozzle projecting downwardly therefrom with three or more spaced fingers at the peripheiy of said nozzle adapted to receive a core.

10. A combination as defined in claim 8 in which a vacuum manifold is connected through a series of openings and tubes to each core-transfer body respectively, means connecting said vacuum manifold to a source of pressure below atmospheric, and laterally and circumferentially adjustable means moving in relation to said tables to connect said tube to vacuum and disconnect said tubes from vacuum to atmosphere respectively at the pick up and discharge portions of said core feeder table and die table.

11. A combination as defined in claim 10 in which the control means comprises a rotating body mounted on a rotating column passing downwardly between said sprocket wheels.

12. A combination as defined in claim 10 in which a source of air, greater than atmospheric pressure is provided, and means associated with said manifold is disposed to connect said tubes with said source of pressure at a point between the deposit location and the pick up location for the core.

13. A combination as defined in claim 1 inwhich a plurality of punches are disposed in pairs in rotating heads above and below said die tables, each pair of punches adapted to register with a die bore in said die table, and means for controlling the level of said punches throughout the rotational circuit of said die heads.

14.111 a compression coating machine of the type utilizing a die pocketed rotary head, its complementary top and bottom punches, a bottom layer granulation feed, and a top layer granulation feed, that improvement in a top granulation feed mechanism which comprises a top layer granulation metering table operating on axis parallel to the head, and positioned to overlap at one peripheral point, said table being circumferentially pocketed with perforations positioned to overlie the pockets of the dies as the two parts rotate, means for filling a metered top granulation feed charge in the perforations of said table as they approach the pocketed head, and means for retaining said charge in the perforations of said table until they overlie the die head.

15. In a compression coating machine of the type utilizing a die pocketed rotary compression table, its complementary top and bottom punches, a bottom granulation feed, and a top granulation feed, that improvement in a core feed mechanism which comprises a pick-up rotary table revolving near the compression table, a continuous member moving in peripheral contact with both tables, and means on said continuous member to select cores from said core feeder table and impress them into a metered bottom charge within die pockets of the compression table while both tables are moving.

16. A device as defined in claim 15 in which means is provided to guide said continuous member in a defined path between said tables.

17. A device as defined in claim 15 in'which said continuous member is driven by said tables.

18. A device as defined in claim 15 in which the last means comprises a plurality of core-transfer assemblies on said continuous member moving in a path to overlie said tables selectively, and means on said transfer assemblies to engage a core to transfer the core from one table to another.

19. A device as defined in claim 18 in which the pick-up table comprises a rotating central disc, a concentric outer ring overlying a portion of the periphery of said disc, said ring having a plurality of spaced notches for receiving and positioning cores relative to the path of said continuous member, a source of airbelow atmospheric pressure, and a suction nozzle on each pick-up body connected to said source adapted to register With said notches as the continuous member moves over the periphery of the pick-up table.

20. A device as defined in claim 19 in which stationary means underlies said notches to form a supporting path for selected cores.

21. In a compression coating machine of the type utilizing a die pocketed rotary compression table, its complementary top and bottom punches, a bottom granulation feed, and a top granulation feed, that improvement in a core feed mechanism which comprises a pick up rotary table revolving near the compression table, a continuous member moving in a peripheral contact with both tables, means on said continuous member to select cores from said core feeder table and impress them into a metered bottom charge within die pockets of the compression table while both tables are moving, said means comprising a plurality of suction nozzles on said continuous member, means which supply suction to said nozzles during a predetermined portion of the travel of said nozzles, means for supplying air under pressure to said nozzles during a portion of their travel between the deposit and the pickup portions of their path, and means responsive to unusual pressure in said nozzles for stopping said machine.

22. A device as defined in claim 21 in which a tube is connected to a source of pressure to direct pressure to said nozzles during a portion of their travel, and a pressure responsive means pneumatically associated with said tube to reflect increased pressure due to a blocked nozzle, and means responsive to said increased pressure for stopping the machine.

23. In a compression coating machine of the type utilizing a die pocketed rotary compression table, its complementary top and bottom punches, a bottom granulation feed, and a top granulation .feed, that improvement in a core feed mechanism which comprises means for providing a supply of cores to be coated, a continuous member moving in peripheral contact with both tables, and vertically shiftable means on said continuous member to select cores from said supply, said means being movable downwardly into the die pockets substantially below the surface of the die pockets to impress the cores into the surface of a metered bottom charge, and means for clearing each of said nozzles after said downward motion comprising a tube associated with each nozzle and a pressure manifold for associating each tube with a source of pressure during a portion of the travel of the continuous member.

24. A device as defined in claim 23 in which a pressure responsive means is associated with each of said tubes during a portion of its travel wherein increased pressure in said tube reflecting a blocked nozzle will actuate said pressure responsive means and cause stopping of said machine.

25. A device as defined in claim 23 in which a sensing finger is positioned to sweep the area directly below said 'nozzles after a deposit motion, said finger being associated with means for stopping said machine in response to the presence of an undeposited core.

26. In a compression coating machine of the type utilizing a die pocketed rotary compression table, its complementary top and bottom punches, a bottom granulation feed, and a top granulation feed, that improvement in a core feed mechanism which comprises a pickup rotary feeder table revolving near the compression table, a continuous member moving in peripheral contact with both tables, and means on said continuous member to select cores from said core feeder table and impress them into a metered bottom charge within die pockets of the compression table while both tables are moving, said core tablet feeder table comprising a rotating central of the periphery of said disc, said ring having a plurality of spaced notches for receiving and positioning cores relative to the path of said continuous member.

27. The method of operating a continuously operating automatic tablet coating.machine, which machine has a die wheel with spaced pockets, spaced pairs of upper and lower die punches cooperating with said die pockets, means for continuously supplying cores to said pockets, means to supply coating material to said pockets, and means to control the relation of said punches to said pockets, the said method comprising, depositing a quantity of coating material into said pockets into the lower punch, strickling the edges of the pocket of the die wheel to gauge the quantity of coating material in each pocket, lowering the lower punch and the gauged coating material in the wheel to make room for a core and a second quantity of coating material, positioning a core on the lowered material, maintaining the core and measured coating material at the lowered level, depositing a second quantity of coating material into the die pockets on the first quantity and the core, and then compressing the two quantities of material around the core.

References Cited in the file of this patent UNITED STATES PATENTS 2,700,938 Wolff et a1 Feb. 1, 1955 2,748,424 Fay June 5, 1956 2,795,199 White June 11, 1957 FOREIGN PATENTS 1,072,611 France Mar. 17, 1934 475,093 Germany Apr. 17, 1929 731,600 Great Britain June 8, 1955 

